Liquid discharge head

Abstract

A recording head includes a pressure chamber and a piezoelectric actuator configured to change a volume of the pressure chamber. The piezoelectric actuator includes a vibration plate forming one wall surface of the pressure chamber, a lower electrode formed on the vibration plate, a piezoelectric body formed on the lower electrode, and an upper electrode formed on the piezoelectric body and the vibration plate. When viewed from a ±Z direction orthogonal to the vibration plate, the lower electrode and the piezoelectric body do not overlap a central portion of the pressure chamber, when viewed from the ±Z direction, the lower electrode, the piezoelectric body, and the upper electrode overlap an end portion of the pressure chamber, and when viewed from the ±Z direction, the upper electrode overlaps the central portion of the pressure chamber.

What is claimed is: 
     
       1. A liquid discharge head, comprising:
 a pressure chamber; and 
 a piezoelectric actuator configured to change a volume of the pressure chamber, wherein 
 the piezoelectric actuator includes a vibration plate forming one wall surface of the pressure chamber, a lower electrode formed on the vibration plate, a piezoelectric body formed on the lower electrode, and an upper electrode formed on the piezoelectric body and the vibration plate, 
 when viewed from a first direction orthogonal to the vibration plate, the lower electrode and the piezoelectric body do not overlap a central portion of the pressure chamber, 
 when viewed from the first direction, the lower electrode, the piezoelectric body, and the upper electrode overlap an end portion of the pressure chamber, 
 when viewed from the first direction, the upper electrode overlaps the central portion of the pressure chamber, and 
 when viewed from the first direction, the piezoelectric actuator includes a protective film formed on the upper electrode and the piezoelectric body outside the end portion of the pressure chamber. 
 
     
     
       2. The liquid discharge head according to  claim 1 , wherein
 when viewed from the first direction, a first end surface of the piezoelectric body arranged between the central portion of the pressure chamber and the end portion of the pressure chamber is closer to the central portion of the pressure chamber than a second end surface of the lower electrode arranged between the central portion of the pressure chamber and the end portion of the pressure chamber, and 
 a distance between the first end surface of the piezoelectric body and the second end surface of the lower electrode is equal to or greater than a thickness of the piezoelectric body on the lower electrode. 
 
     
     
       3. The liquid discharge head according to  claim 1 , wherein
 the protective film covers a first surface of the upper electrode on an opposite side of the piezoelectric body and the vibration plate, and a side surface intersecting the first surface. 
 
     
     
       4. The liquid discharge head according to  claim 1 , wherein
 a plurality of the pressure chambers and the piezoelectric actuators are formed, 
 the lower electrode is an individual electrode formed for each of the piezoelectric actuators, and 
 the upper electrode is a common electrode common to the plurality of piezoelectric actuators, and covers a second surface of the piezoelectric body on an opposite side of the lower electrode and a side surface intersecting the second surface.